Everybody was concerned last week when it was announced that a nasty bug in OS X was leaving Macs vulnerable to attacks that could grab information traveling across shared networks. While it has been confirmed that the bug only affected Mavericks, Apple simultaneously posted security updates for Mountain Lion (10.8) and Lion (10.7), but there was no sign of any security love for Snow Leopard (10.6). This really shouldn’t be a surprise to most people since 10.6 was also skipped when a previous security update was released as well as an update to the Safari browser. The omission of 10.6 from the current update simply confirms that Snow Leopard is no longer on Apple’s radar.

It’s not terribly unexpected given that 10.6 was released in 2009, which is nearly a five year stint. As a matter of fact, historically Apple drops support for OS X sooner, only supporting the current version and the previous one. So for a brief time, Apple was supporting four OSes instead of two, which with Snow Leopard gone still leaves three (isn’t my math impressive?) meaning this was a long time coming. So, why does this matter since you can get Mavericks for free now? As a few other tech bloggers have pointed out, OS X 10.6 is the equivalent to Microsoft’s Windows XP, not in performance and features, but in its popularity and flexibility to run legacy software. Two key things make Snow Leopard indispensable for some users; while it could no longer run “Classic” applications, it was the last version of OS X capable of running software written for the PowerPC chip by using the Rosetta framework, which was software that pretended to be a PowerPC chip while it was running on the new Intel chip architecture. Secondly, it was the last version that was capable of running on 32-bit systems (newer Macs have 64-bit systems). Because of these features that keep older software alive, Snow Leopard’s user base has not dropped off dramatically in the last few years, unlike many Lion and Mountain lion users who took advantage of the free update to Mavericks. This means 10.6 is still running on a lot of Macs, and without security updates, this leaves roughly one out of every five Macs vulnerable to a handful of OS weaknesses that won’t be patched. For any companies that have to run the older system on machines for compatibility, it could make things difficult for IT staff to support these machines.

Unfortunately for some, the wheels of progress continue to roll on. If you are someone who still needs to use Snow Leopard, you may want to take some additional precautions. Use OS X’s built-in firewall to help keep potential invaders from getting to your machine, and enable Stealth Mode. The firewall controls are under Security and Privacy in System Preferences. Stealth mode will be available when the firewall is turned on. You may also consider shutting down your computer if you won’t be using it for an extended time, or disconnect it from your network while it’s idle. There is also a great article at Ars Technica about your upgrade options in case you’ve just never gotten around to moving past 10.6. It also has some tips for Snow Leopard if you just can’t move on.

Watch out Lion users! OS X 10.7 is up next for the chopping block, but who knows when?